我在刷卡刷新布局中使用Recycler视图作为单个子项。最初，在从Web服务向上和向下加载数据时，它不能平滑滚动。但是在第一次滚动之后，它会顺利滚动。如何让它在第一次滚动时顺畅滚动。
private RecyclerView newsFeedList;
newsFeedList = (RecyclerView) view.findViewById(R.id.rv_feed_list);
newsFeedList.setHasFixedSize(true);
LinearLayoutManager llm = new LinearLayoutManager(getActivity());
llm.setOrientation(LinearLayoutManager.VERTICAL);
newsFeedList.setLayoutManager(llm);
newsFeedAdapter = new NewsFeedAdapter(getActivity(), new ArrayList<NewsFeedParser.NewsFeed>(), newsFeedList);
newsFeedList.setAdapter(newsFeedAdapter);
并在通过调用以下方法从Web服务获得响应后更新了recyclerview：
private void parseDataToNewsFeed(String response, boolean isLoadMore) {
Gson gson = new Gson();
NewsFeedParser newsFeedParser = gson.fromJson(response, NewsFeedParser.class);
if (newsFeedParser.data != null && newsFeedParser.data.size() > 0) {
if (isLoadMore) {
newsFeedAdapter.removeProgress(newsFeedAdapter.getItemCount());
newsFeedAdapter.addList(newsFeedParser.data);
} else {
currentPageCount = 1;
newsFeedAdapter.updateList(newsFeedParser.data);
}
} else {
newsFeedAdapter.updateList(newsFeedParser.data);
txtNoResult.setText(getString(R.string.no_clubs_socities_subscribed));
txtNoResult.setVisibility(View.VISIBLE);
}
}
Adaper课程：
public class NewsFeedAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private final DisplayImageOptions options;
private Context context;
private ArrayList<NewsFeedParser.NewsFeed> itemList;
private int lastVisibleItem, totalItemCount, visibleThreshold = 2;
private boolean loading;
public OnLoadMoreListener onLoadMoreListener;
private OnItemClickListener itemClickListener;
// private ImageLoader mImageLoader;
private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 0;
private long mLastClickTimeListViewItem = 0;
public NewsFeedAdapter(Context context, ArrayList<NewsFeedParser.NewsFeed> itemList, RecyclerView recyclerView) {
this.context = context;
this.itemList = itemList;
options = new DisplayImageOptions.Builder()
.showImageOnLoading(R.drawable.ic_default_news)
.showImageForEmptyUri(R.drawable.ic_default_news)
.showImageOnFail(R.drawable.ic_default_news)
.cacheInMemory(true)
.cacheOnDisk(true)
.considerExifParams(true)
.bitmapConfig(Bitmap.Config.RGB_565)
.build();
if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
totalItemCount = linearLayoutManager.getItemCount();
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
if (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
loading = true;
}
}
});
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
RecyclerView.ViewHolder vh;
if (viewType == VIEW_ITEM) {
View itemView = LayoutInflater.from(context).inflate(R.layout.fragment_news_feed_trending_list_item, parent, false);
vh = new NewsFeedViewHolder(itemView);
} else {
View progView = LayoutInflater.from(context).inflate(R.layout.view_refresh_footer, parent, false);
vh = new ProgressViewHolder(progView);
}
return vh;
}
@Override
public int getItemViewType(int position) {
return itemList.get(position) != null ? VIEW_ITEM : VIEW_PROG;
}
@Override
public int getItemCount() {
return itemList.size();
}
@Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, final int position) {
if (holder instanceof NewsFeedViewHolder) {
final NewsFeedParser.NewsFeed singleItem = itemList.get(position);
((NewsFeedViewHolder) holder).txtNews.setText(Html.fromHtml(singleItem.title));
((NewsFeedViewHolder) holder).txtDays.setText(DateConversion.getStatusTiming(context, singleItem.modified));
((NewsFeedViewHolder) holder).imgNewsPhoto.setImageResource(R.drawable.ic_default_news);
if (singleItem.featured_image != null) {
if (singleItem.featured_image.attachment_meta != null) {
if (singleItem.featured_image.attachment_meta.sizes != null) {
if (singleItem.featured_image.attachment_meta.sizes.thumbnail != null) {
if (!TextUtils.isNullOrEmpty(singleItem.featured_image.attachment_meta.sizes.thumbnail.url)) {
ImageLoader.getInstance().displayImage(singleItem.featured_image.attachment_meta.sizes.thumbnail.url, ((NewsFeedViewHolder) holder).imgNewsPhoto, options);
} else {
if (!TextUtils.isNullOrEmpty(singleItem.featured_image.source)) {
ImageLoader.getInstance().displayImage(singleItem.featured_image.source, ((NewsFeedViewHolder) holder).imgNewsPhoto, options);
}
}
}
}
}
}
if (singleItem.read_status == 0) {
((NewsFeedViewHolder) holder).rlFeedItem.setBackgroundColor(ContextCompat.getColor(context, R.color.clr_news_feed_item_bg));
} else {
((NewsFeedViewHolder) holder).rlFeedItem.setBackgroundColor(ContextCompat.getColor(context, R.color.transparent));
}
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (SystemClock.elapsedRealtime() - mLastClickTimeListViewItem < 1000) {
return;
}
mLastClickTimeListViewItem = SystemClock.elapsedRealtime();
if (itemClickListener != null) {
itemClickListener.onItemClick(singleItem);
singleItem.read_status = 1;
notifyItemChanged(position);
}
}
});
} else {
((ProgressViewHolder) holder).progressBar.setLinearProgress(true);
}
}
public void addList(ArrayList<NewsFeedParser.NewsFeed> items) {
if (items == null) {
this.itemList.add(null);
} else {
for (NewsFeedParser.NewsFeed item : items) {
this.itemList.add(item);
}
}
notifyDataSetChanged();
}
public void updateList(ArrayList<NewsFeedParser.NewsFeed> items) {
if (items != null) {
this.itemList = items;
}
notifyDataSetChanged();
}
public void removeProgress(int itemCount) {
this.itemList.remove(itemCount - 1);
notifyItemRemoved(itemCount);
}
public static class NewsFeedViewHolder extends RecyclerView.ViewHolder {
USUTextView txtNews, txtDays;
ImageView imgNewsPhoto;
RelativeLayout rlFeedItem;
public NewsFeedViewHolder(View itemView) {
super(itemView);
txtNews = (USUTextView) itemView.findViewById(R.id.txt_news);
txtDays = (USUTextView) itemView.findViewById(R.id.txt_days);
imgNewsPhoto = (ImageView) itemView.findViewById(R.id.img_news_photo);
rlFeedItem = (RelativeLayout) itemView.findViewById(R.id.rl_feed_list_item);
}
}
public static class ProgressViewHolder extends RecyclerView.ViewHolder {
public ProgressWheel progressBar;
public ProgressViewHolder(View progView) {
super(progView);
progressBar = (ProgressWheel) progView.findViewById(R.id.progress_bar);
}
}
public void setLoaded() {
loading = false;
}
public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
this.onLoadMoreListener = onLoadMoreListener;
}
public interface OnLoadMoreListener {
void onLoadMore();
}
public void setOnItemClickListener(OnItemClickListener recyclerClickListener) {
this.itemClickListener = recyclerClickListener;
}
public interface OnItemClickListener {
void onItemClick(NewsFeedParser.NewsFeed item);
}
}
请建议我任何想法.....